An extensive evaluation flow cytometric evaluation continues of patients with autoimmune lymphoproliferative syndrome (ALPS) and their extended-family members. The evaluation is based on characterization of the expanded double negative T-cell and B-cell populations. To date, the double negative T-cells have been demonstrated to be alpha beta TcR, CD57+, HLA-DR+, and CD45RA+. This study has been extended to characterize the double negative T cells more completely including gamma-delta TcR T cells in all ALPS patients. In addition, expanded characterization of the B cells in these patients has also been initiated.